A. Abstract and Key Personnel Three Research Cores are proposed to facilitate interdisciplinary research into hearing and deafness at the Massachusetts Eye and Ear Infirmary. The three Cores and the major aims of each include 1) an Engineering Core to design, build, program and maintain data-acquisition systems, custom acoustical devices, and stimulus generation systems, and to provide a precision machining service to build custom mechanical devices for a wide variety of research applications; 2) an Imaging Core to support the needs of Center investigators for digital image-acquisition and analysis, including confocal microscopy, transmission electron microscopy, computer-aided anatomical reconstruction, automation of morphometry, 3-D reconstruction/rendering, and analysis of functional imaging data; and 3) a Histology-Surgery Core to maintain existing shared facilities and assist research teams in animal surgery and histological preparation for both light and electron microscopy. The Administrative Shell for this P30 includes the Program Director and a Grants Manager. Only fractional additional effort level is required to effectively administer this P30, because 1) the Center Investigators, Core Personnel, Program Director and Grants Manager have a long history of productive collaboration, 2) the Program Director is also Co-PI on both Imaging and Histology-Surgery Cores and is an active user of the Engineering Core, and 3) the Grants Manager also handles many pre-award and postaward functions for the numerous R-grants of almost all Center Investigators and is thus thoroughly conversant with all the components of this Center.